1. Field of the Invention
This invention relates to apparatus and methods for therapeutic intervention of the complex immune response in rheumatoid and psoriatic arthritis.
2. Background Summary
Arthritis is a general term that encompasses several distinguishable joint disorders, such as osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis.
Osteoarthritis, also known as degenerative joint disease, is caused by long-term wear and tear on the protective cartilage that lines the inner surfaces of joints. Although typically a disorder of old age, certain predisposing conditions can hasten the degenerative process in younger persons. Symptoms may include joint aching and stiffness, with x rays showing a narrowing of the joint space and new bone formation adjacent to the joint. Treatment includes anti-inflammatory medication, heat, and physical therapy; in severe cases refractory to conservative treatment surgery, including joint replacement, may be necessary.
Rheumatoid arthritis (RA) is a chronic inflammatory condition that is believed to be an autoimmune disease, since an antibody, rheumatoid factor (RF), is present in the bloodstream of a majority of patients. The level of RF in the patient correlates with the severity of the disease. This antibody may be formed in response to an antigen that triggers a complex immune response, causing white blood cells and antibodies to infiltrate the synovial membranes. The resulting recurrent inflammation causes permanent damage to the joint cartilage, bones, ligaments, and tendons. Conventional wisdom suggests a genetic component that predisposes RA tendencies among Nordic, Celtic, and Slavic populations, and appears between the ages of 20 and 70, mostly in women. The symptoms include joint pain, aching, and stiffness, followed by joint swelling, redness, and warmth. Rheumatoid nodules may appear beneath the skin, especially around the elbow and sometimes the spine. Treatment usually consists of anti-inflammatory and immunosuppresant medication and short-term courses of asteroid such as prednisone. While these medications decrease joint inflammation, they do not alter the course of the disease. Remission-inducing and chemotherapy drugs are available for long-term use, but they are associated with potentially dangerous, even lethal, side effects. For instance, nonsteroidal anti-inflammatory drugs are know to cause digestive tract bleeding, and methodtrexate, an antineoplastic, can cause hepatotoxicity (liver cell damage) and pancytopenia (aplastic anemia). Artificial joint replacement is used in severe cases.
Ankylosing spondylitis (AS) is an inflammatory condition of the spine and sacroiliac joints. The hallmark of this disease is the bony fusion (ankylosis) of the spinal vertebrae, leading to permanent loss of flexibility of the back and neck. Other joints and tissues may also be affected by the inflammatory process. AS occurs most often in men between the ages of 20 and 40, and rarely is found after age 50. The cause of as is unknown, but a genetic predisposition is suspected. Pain and stiffness localized to the lower back and sacroiliac joints adjacent to the spine are the most common early manifestations, with arthritis in the hip, shoulder, or other joints also presenting. Gradually spinal immobility occurs, resulting in spinal deformity and decreased chest expansion. Treatment includes physical therapy and nonsteroidal anti-inflammatory medication, neither of which has a direct effect on the course of the disease.
Psoriatic arthritis, which is an arthritic condition associated with psoriasis, has similar symptoms to rheumatoid arthritis. While psoriasis and rheumatoid arthritis do indeed coexist in some patients, psoriatic arthritis is a distinct disease entity, with rheumatoid factor being absent. Treatment includes the use of salicylates and physical therapy, with adrenocorticosteroid drugs being administered as a last resort. Severe cases may be treated with immunosuppressants, which may be toxic. Severe psoriatic arthropathy not responsive to conventional antirheumatic therapy may be treated with methotrexate, although careful surveillance for evidence of myelosuppression, pancytopenia, and hepatotoxicity is required.